Solar photovoltaic installations in the US have passed the 10 gigawatt plateau, making it the fourth country to reach that level of solar power.

Solar photovoltaic installations has been one of the fastest growing energy sources in the US over the past six years, with a compound annual growth rate of over 50% since 2007, according to NPD SolarBuzz, a market analysis firm.

Solar PV installations are forecast to increase an additional 80% over the next 18 months, surpassing 17 gigawatts by the end of 2014, according SolarBuzz forecasts.

“The US has now joined an elite group of maturing solar PV markets that have accumulated more than 10 GW of installed capacity,” said Christopher Sunsong, analyst at NPD Solarbuzz. “Only Germany, Italy, and China have more installed PV capacity than the US. The US is only the fourth country to reach the 10 GW milestone.”